I am looking for my doughter she was adopted her name is helen ann williams d.o.b 15/4/1991

Where were you at when she got adopted??

Since this is an international site, much more information is needed.

If you are an American, then you have to wait a few more months.

Most search sites won't allow you to start a search until your child is 18 and an adult.

While you can leave your information at the courthouse in the county where she was born/adopted and with the adoption agency used, I do not believe she can access ANY of it until she is 18.

And no private investigator is going to help you find a minor not related to you by law.